Flow cytometer with active automated optical alignment system

1. A flow cytometer optical alignment system, comprising:

a. a target;

b. an electromagnetic radiation emission source;

c. an electromagnetic radiation beam emitted from said electromagnetic radiation emission source directionally responsive to at least one optical element;

d. a electromagnetic radiation beam direction sensor having a surface located to receive a portion of said electromagnetic radiation beam, wherein incidence of said portion of said electromagnetic radiation beam on said surface generates an electromagnetic radiation beam position signal; and

e. a position control device coupled to said at least one optical element, wherein said position control device responds to an electromagnetic radiation beam direction correction signal to directionally control said optical element to align said electromagnetic radiation beam.

2. A flow cytometer optical alignment system as described in claim 1 , wherein said electromagnetic radiation beam direction sensor samples a portion of said electromagnetic radiation beam at a location between said at least one optical element and said target.

3. A flow cytometer optical alignment system as described in claim 1 , wherein said electromagnetic radiation beam direction sensor samples a portion of said electromagnetic radiation beam after incidence of said electromagnetic radiation beam on said target.

4. A flow cytometer optical alignment system as described in claim 2 or 3 , wherein said electromagnetic radiation beam direction sensor comprises a quadrant photodiode sensor.

5. A flow cytometer optical alignment system as described in claim 1 , further comprising a fluid stream, wherein said target comprises a location in said fluid stream, and wherein said electromagnetic radiation beam aligns with said location in said fluid stream.

6. A flow cytometer optical alignment system as described in claim 5 , further comprising particles entrained in said fluid stream, wherein said electromagnetic radiation beam aligned with said location in said fluid stream irradiates at least one of said particles entrained in said fluid stream.

7. A flow cytometer optical alignment system as described in claim 1 , further comprising a nozzle having a nozzle aperture, wherein said fluid stream exits through said nozzle aperture.

8. A flow cytometer optical alignment system as described in claim 7 , further comprising:

a. a second optical element to which said electromagnetic radiation beam emitted from said electromagnetic radiation emission source is directionally responsive;

b. a second electromagnetic radiation beam direction sensor having a surface positioned to receive a portion of said electromagnetic radiation beam, wherein incidence of said portion of said electromagnetic radiation beam on said surface generates an electromagnetic radiation beam direction correction signal; and

c. a second optical orientation element coupled to said at least one optical element, wherein said second optical orientation element responds to said electromagnetic radiation beam direction correction signal to automatically align said electromagnetic radiation beam on said target.

9. A flow cytometer optical alignment system as described in claim 7 , wherein said electromagnetic radiation beam direction sensor samples a portion of said electromagnetic radiation beam at a location between said at least one optical element and said target.

10. A flow cytometer optical alignment system as described in claim 1 , wherein said electromagnetic radiation beam direction sensor samples a portion of said electromagnetic radiation beam after incidence of said electromagnetic radiation beam on said target.

11. A flow cytometer optical alignment system as described in claim 1 , further comprising:

a. a electromagnetic radiation polarization element;

b. a beam of electromagnetic radiation emitted from said target coaxial to said excitation path responsive to said electromagnetic radiation polarization element;

c. a polarization sensitive reflecting element that reflects said beam of electromagnetic radiation emitted from said target polarized by said electromagnetic radiation polarization element; and

d. an image representation capture device responsive to said electromagnetic radiation emitted from said target polarized by said electromagnetic radiation polarization element.

12. A flow cytometer optical alignment system as described in claim 1 , further comprising:

a. an illumination element positioned to provide illumination of said fluid stream;

b. an electromagnetic radiation emission generated by said particle;

b. an image screen incident to said electromagnetic radiation emission generated by said particle and said illumination of said fluid stream;

c. an image generated on said image screen of said electromagnetic radiation emission generated by said particle and said illumination of said fluid stream;

d. at least one image screen aperture through which at least part of said electromagnetic radiation emission generated by said particle passes;

e. a receiver incident to said at least part of said electromagnetic radiation emission generated by said particle; and

f. an image representation capture device responsive to said image generated on said image screen, wherein said image representation capture device generates a electromagnetic radiation beam position signal.

13. A flow cytometer optical alignment system as described in claim 1 , further comprising:

a. at least one memory storage element responsive to said electromagnetic beam position signal;

b. a retrieval element to retrieve said electromagnetic beam position signal from said at least one memory storage element;

c. an electromagnetic beam position signal analysis element; and

d. a controller that provides electromagnetic radiation beam position correction signal to position control devices coupled to said at least one optical element.

14. A flow cytometer, comprising:

a. a nozzle having an nozzle aperture;

b. a fluid stream which exits said nozzle through said nozzle aperture;

c. a droplet generator to which said fluid stream responds by forming droplets, wherein said droplets have a break off point a distance from said nozzle aperture;

d. electromagnetic radiation beam having a path through said fluid stream between said nozzle aperture and said break off point;

e. at least one optical element to which said electromagnetic radiation beam is directionally responsive;

f. a electromagnetic radiation beam position sensor having a surface located to receive a portion of said electromagnetic radiation beam, wherein incidence of said portion of said electromagnetic radiation beam on said surface generates an electromagnetic radiation beam position signal; and

g. a position control device coupled to said at least one optical element, wherein said position control device responds to an electromagnetic radiation beam direction correction signal to directionally control said optical element to align said electromagnetic radiation beam.

15. A method of controlling the direction of an electromagnetic radiation beam of a flow cytometer, comprising the steps of:

a. emitting an electromagnetic radiation beam directionally responsive to an optical element;

b. sampling a portion of said electromagnetic radiation beam to a surface positionally sensitive to incidence of said electromagnetic radiation beam;

c. generating an electromagnetic radiation beam position signal corresponding to position of said incidence of said electromagnetic radiation beam on said surface;

d. analyzing said electromagnetic radiation beam position signal;

e. determining alignment error of said electromagnetic radiation beam to a target;

f. generating an electromagnetic radiation beam direction correction signal; and

g. adjusting said optical element to correct alignment error of said electromagnetic beam with a target location.

16. A method of controlling the direction of an electromagnetic radiation beam of a flow cytometer as described in claim 15 , further comprising the step of streaming a fluid through said target location.

17. A method of controlling the direction of an electromagnetic radiation beam of a flow cytometer as described in claim 15 , further comprising the step of entraining at least one particle in said fluid, wherein said electromagnetic radiation beam irradiates said particle at said target location.